This invention relates to a vehicle motion control device which is applicable to a brake steering control device, a traction control device and so on.
A Japanese Patent Laid-Open Publication No. 7-304436 discloses a vehicle motion control device of this kind. This known device includes a wheel cylinder equipped on a vehicle wheel, an automatic hydraulic pressure generator generating a brake hydraulic pressure irrespective of the operation of a brake pedal by using an intake vacuum pressure of an engine of a vehicle, a hydraulic pressure control valve disposed between the wheel cylinder and the automatic hydraulic pressure generator, a throttle opening amount automatic adjusting means for adjusting automatically the opening amount of a throttle valve of the engine irrespective of the operation of an accelerator pedal of the vehicle and control means for controlling the automatic hydraulic pressure generator and the hydraulic pressure control valve in accordance with a running condition of the vehicle and for performing an automatic pressure increase control to the wheel cylinder at least when the brake pedal is not operated. Further, the control means controls the throttle opening amount automatic adjusting means in accordance with the running condition of the vehicle and performs an opening amount automatic adjust control to the wheel cylinder.
In the vehicle motion control device of this kind, when the automatic pressure Increase control is performed intermittently at relative shorter intervals, the vacuum pressure in the automatic hydraulic pressure generator is dissipated excessively and is decreased. As a result, the brake hydraulic pressure which the automatic hydraulic pressure generator can generate is decreased and the performance of the vehicle motion control device decreases. Further, a brake operational force which is required for normal braking is increased.
A need thus exists for a vehicle motion control device which lessens the decrease of the vacuum pressure in the automatic hydraulic pressure generator when the automatic pressure increase control is performed intermittently at relative shorter intervals.
In light of the foregoing, the present invention provides a vehicle motion control device which includes a wheel cylinder equipped on a vehicle wheel; an automatic hydraulic pressure generator generating a brake hydraulic pressure irrespective of the operation of a brake pedal by using an intake vacuum pressure of an engine of a vehicle; a hydraulic pressure control valve disposed between the wheel cylinder and the automatic hydraulic pressure generator; a throttle opening amount automatic adjusting means for adjusting automatically the opening amount of a throttle valve of the engine irrespective of the operation of an accelerator pedal of the vehicle; control means for controlling the automatic hydraulic pressure generator and the hydraulic pressure control valve in accordance with a running condition of the vehicle and for performing an automatic pressure increase control to the wheel cylinder at least non-operating condition of the brake pedal, the control means for controlling the throttle opening amount automatic adjusting means in accordance with the running condition of the vehicle and for performing an opening amount automatic adjust control to the wheel cylinder; intake vacuum pressure decrease condition detecting means for detecting a decrease condition of the intake vacuum pressure; and counter means for counting the number of performance of the automatic pressure increase control performed under the intake vacuum pressure decrease condition detected by the intake vacuum pressure decrease condition detecting means, wherein the control means corrects the throttle opening amount requested to the throttle opening amount automatic adjusting means at the automatic pressure increase control so as to decrease in accordance with the number of performance of the automatic pressure increase control counted by the counter means.